The Babylonian Jews and Nestorian Christians sided with Ali, and rendered him assistance. A Jew, Abdallah Ibn-Sabâ, was a spirited partisan of Ali. He asserted that the succession to the Caliphate was his by right, and that the divine spirit of Mahomet had passed to him, as it had from Moses to Joshua. It is said that when Ali took the town of Firuz-Shabur or Anbar, 90,000 Jews, under Mar-Isaac, the head of a college, assembled to do homage to the Caliph, who was but indifferently supported by his own followers (658). The unhappy Ali valued this homage, and, doubtless, accorded privileges to the Jewish principal. It is quite probable that from this time the head of the school of Sora was invested with a certain dignity, and took the title of Gaon. There were certain privileges connected with the Gaonate, upon which even the Exilarch did not venture to encroach. Thus a peculiar relation, leading to subsequent quarrels, grew up between the rival offices--the Exilarchate and the Gaonate. With Bostanaï and Mar-Isaac, the Jewish officials recognized by the Caliph, there begins a new period in Jewish history--the Epoch of the Geonim. After Bostanaï's death dissension arose among his sons. Bostanaï had left several sons by various wives, one of them the daughter of the Persian king. Perhaps her son was his father's favorite, because royal blood flowed in his veins, and he was probably destined to be his successor. His brothers by the Jewish wives were consequently jealous of him, and treated him as a slave, _i. e._, as one that had been born of a captive non-Jewess, who, according to Talmudic law, was looked upon as a slave, so long as he could not furnish proof that either his mother or himself had been formally emancipated. This, however, he could not do. The brothers then determined to sell the favorite, their own brother, as a slave. Revolting as this proceeding was, it was approved by several members of the college of Pumbeditha, partly from religious scruples, partly from the desire to render a friendly service to Bostanaï's legitimate sons. Other authorities, however, maintained that Bostanaï, who was a pious man, would not have married the king's daughter before he had legally freed her, and made her a proselyte. In order to protect her son from humiliation, one of the chief judges, Chaninaï, hastened to execute a document attesting her emancipation, and thus the wicked design of the brothers was frustrated; but the stain of illegitimacy still attached to the son, and his descendants were never admitted to the rank of the descendants of the Exilarch Bostanaï.